1. Field of the Invention
This invention is directed to an airflow regulating system and more particularly to an apparatus that is useful in purifying contaminated air for assisting persons to breathe in hostile environments.
2. Background of the Invention
There are, at present breathing systems for assisting the breathing of persons who are subject to contaminated air. There are filter/decontamination systems for use in the form of a canister, in connection with a respirator apparatus that rely on cleaning ambient atmosphere to make it suitable for breathing. Such filter systems may or may not make use of auxiliary power. In powered systems, ambient atmosphere is sucked through a suitable filter/decontamination means, or other purifying means, by a powered fan or the like, such that the contaminated ambient air is rendered breathable. The purified resultant air is fed to a headpiece of some kind, such as a tight fitting facemask. The complete system is known as a Powered Air Purifying Respirator (PAPR). Such breathing assists are used by personnel who are subject to breathing ambient atmosphere that would otherwise be considered to be harmfully contaminated, un-breathable, or dangerous air. Firefighters and others in the emergency response arena may use PAPRs equipped with filter canisters, such as HEPA filters, to provide filtered ambient air to any user who is operating in a hazardous environment.
A dangerous or un-breathable atmosphere is considered to be air containing less than 19.5 volume percent oxygen, or air with the requisite oxygen, but also containing significant proportions of harmful contaminants, e.g. particulate or gaseous. A PAPR system will protect against contaminants so long as the oxygen level in the purified air is above 19.5 volume percent and provided the contaminants are such as can be removed by filtration, e.g. soot and smoke, and/or can be ameliorated by reaction with a suitable purifying material. In practical effect, these systems have been designed to use replaceable filter(s) and air purifying canister(s). However, they are of no value where the ambient atmosphere has an oxygen content that is less than 19.5% by volume. It will be appreciated that, in some situations, (where the oxygen content is at least 19.5%), a wearer may be able to enter an area that has a contaminated atmosphere using only a filter system, provided the filter(s) is capable of meeting the challenge of the contamination, as a result cleaning the atmosphere and enabling the user to breathe and still preserve his health. The filter can be provided with means to eliminate harmful constituents in the wearer's ambient atmosphere. In particular, filter based decontamination systems, that is, those systems that purify an ambient atmosphere that has become contaminated so as to convert it to breathable air, work best when they pass an air supply under positive pressure through a cleaning element (such as a suitable filter). That is, a pump/fan is used to suck the contaminated atmosphere through a filter, and perhaps into contact with a material that ameliorates the contaminant(s), and to then force the purified, e.g. filtered, air under positive pressure into a facemask or other means associated with the breathing of the wearer, such as a mouth grip, hood, or helmet. While a powered air supplying means, such as a battery-operated pump/fan, is probably preferred, it is also known that air-cleaning systems that are not powered by external means can be used. In these unpowered systems, the user's lung power provides the necessary impetus to force contaminated air through the cleaning element and feed it to the user. For simplicity, this means of cleaning ambient atmosphere will be referred to as an Air Purifying Respirator (APR). When the air is forced through the system due to the use of a battery, line current or other powered pump or fan arrangement, the operating system is known as a Powered Air Purifying Respirator (PAPR).
Given the growing demand for PAPR systems, requirements have been identified for providing breath responsive systems that would allow longer filter life, conservation of battery power, and provide air generally on a demand basis so as to better simulate the user's natural breathing pattern. However, while prior efforts have been made to provide breath-responsive systems, shortcomings of prior constructions have prevented their commercial acceptance.
Thus, there remains a need for a breathing assist system that is capable of supplying breathable air to a user, but that does so while maximizing efficiency of the apparatus and that preferably supplies only the amount of air that the user's actual demand for air dictates.
The above and following comments use a fire fighter as illustrative of the type of person who will benefit from using the instant invention. However, this invention is by no means limited in use to fire fighters. Workers in chemical plants and refineries will have substantial need for the benefits available from the instant invented system. Soldiers in the field that are being subjected to chemical or biological attack will benefit greatly from the instant system. It will be apparent to those of ordinary skill in this art that others will similarly be assisted by the instant invention.